1. Field of the Invention
The present invention relates to an image forming apparatus capable of forming a multicolor image using developers of a plurality of colors.
2. Description of the Related Art
In a multicolor image forming apparatus that carries out multicolor printing using multicolor toners, for example, as shown in FIGS. 6 to 8, a yellow toner use container 900Y supplies toner of its color to a development device 10Y; a magenta toner use container 900M supplies toner of its color to a development device 10M; a cyan toner use container 900C supplies toner of its color to a development device 10C; and a black toner use container 900K supplies toner of its color to a development device 10K. Then, the toner supplied to each of the development devices 10Y, 10M, 10C, and 10K is supplied to an image forming portion. The multicolor image forming apparatus is configured to obtain a multicolor image by superimposing toner images of respective colors.
The development devices (development devices 100, 200, 300, and 400 in FIGS. 6 to 8) used as these development devices 10Y, 10M, 10C, and 10K are removably attached to the apparatus body, so as to be removed from and attached to the apparatus body when they reach their end of life and to be replaced by new development devices, or for the purpose of maintenance check, cleaning and the like of the apparatus.
Accordingly, in order to allow the apparatus body to recognize any development device being attached or removed, the development devices 100, 200, 300, and 400 have generally installed therein EEPROMs (Electrically Erasable Programmable Read Only Memories) 100a, 200a, 300a, and 400a for storing a variety of information (T/C (toner/carrier) data, counter information and the like). Then, data reading/writing or the like is carried out between the EEPROMs 100a, 200a, 300a, and 400a and a CPU 210 on the apparatus body side, through a serial bus such as an I2C bus, such that the attached development device can be recognized on the apparatus body side.
Here, in the following, a description will be given of the processing carried out by a controller 170 when the development device is attached to the apparatus body in the conventional structure described above, with reference to flowcharts of FIGS. 7, 8, and 9.
When the development device 200 is taken out from a port with a communication address 2 of the apparatus body, and a development device 500 is attached to the port with the identical communication address 2, the CPU 210 reads and checks the serial number (the number specific to each development device, such as a manufacturer's serial number) of the attached development device 500 from the EEPROM 500a (S11). In the case shown in FIG. 7, the serial number of the development device 500 attached to the port with the communication address 2 is “500”. Then, it is determined whether or not the “serial No. 500” of the communication address 2 agrees with the serial number corresponding to the communication address 2, which is previously stored in an EEPROM 220 on the body side (S12). In the case shown in FIG. 7, the serial number corresponding to the communication address 2 previously stored in the EEPROM 220 is the “serial No. 200” of the development device 200 which is just removed and, therefore, it disagrees with the “serial No. 500” of the attached development device (NO in S12). In this case, the CPU 210 recognizes that a new development device 500 is attached as the development device 10C, and the development device 500 is supplied with the cyan toner from the cyan toner use container 900C (S13).
Next, the following discusses a case where a plurality of development devices are removed from the apparatus body for the purpose of maintenance or the like, and thereafter reattached to the apparatus body, and on the assumption that, for example as shown in FIG. 8, they are each mistakenly attached to the port with other communication address being different from the port with the original communication address. In FIG. 8, for example, though the development device 300 should have been reattached to the port with the communication address 3, the development device 300 is mistakenly reattached to the port with the communication address 2. In this case, the serial number of the development device attached to the port with the communication address 2 is “300”. While this serial No. 300 is stored in a storage area corresponding to the communication address 3 of the EEPROM 220 on the body side, the serial number stored in a storage area corresponding to the communication address 2 is “200”, which disagrees with the “serial No. 300” of the attached development device 300 (NO in S12).
Accordingly, there is the following disadvantage: despite the fact that the development device 300 just attached is the one having been in use as the development device 10M that supplies the magenta purpose toner to the image forming portion of the apparatus body, and merely temporarily been taken outside the apparatus for the purpose of maintenance or the like, it is mistakenly recognized that the development device 300 is attached as a new cyan toner use development device 10C. In this case, the cyan toner supplied from the cyan toner use container 900C is blended with the magenta purpose toner in the development device 300.
Meanwhile, there is a known technique that can prevent a printing operation from being executed while developers of different colors are blended with each other. This technique is configured such that, at the time point where the development device is attached to the apparatus body, the user operates an operational portion arranged on the apparatus body side to enter an input, to thereby confirm or update the toner replacement history, the type of the replaced developer, the life information of the development device and the like, which are stored in the EEPROM of the development device. However, in this case, every time the development device is attached to the apparatus body, the user must update the information required for making a determination as to whether or not any mistaken attachment takes place, and store the updated information in the EEPROM of the development device. Thus, it is disadvantageous in that it requires troublesome operation and processing. Further, the conventional structure described above is configured to report to the user after the fact of mistaken supply of the developer of a different color to the development device, and it is not configured to prevent such mistaken supply of the developer.